1. Field of the Invention
The present invention relates to a process to be used in the manufacture of electric components, and particularly a process for simultaneously coating a batch of electric components with resin.
2. Description of the Prior Art
It is well known in the electronics industry to coat individual electrical components, such as resistors, capacitors, diodes and the like, with a suitable compound in order to prevent moisture from affecting the operation of the operative portion of the component, and in general to protect the component from shock or other stress. Various types of synthetic resins known in the art can be applied in a viscous fluid form to coat the components, and possess suitable imperviousness to moisture and material strength when hardened.
A problem in coating such electrical components which have lead wires extending therefrom is to coat the component while leaving the lead wires uncovered so that the components can be inserted in a circuit board without the necessity of the additional step of stripping the leads of resin. This is particularly a problem if the leads extend downwardly from a base of the component, because the base of the component must be covered with resin to the same extent as the remainder of the component.
It is known in the art to apply synthetic resin in a viscous fluid form to a mold containing a number of components clampingly held therein by their individual lead wires. Such a method and apparatus is usable only to coat components having lead wires extending from the ends thereof, because no protection would be provided to prevent the resin from flowing over the leads of components which extend from a base of the component.
It is also known in the art to coat a batch of individual electrical components having leads extending from the base of each component by inserting the leads in a flexible sheet, such as one made of silicon rubber, and introducing the entire sheet into a casting mold. Such a sheet must be designed to be relatively soft, so that the lead wires can be pressed or inserted therein, thereby allowing only very rough control of the evenness of the coating applied over the base. The process also does not guarantee exact centering of the component to be coated in the mold, so that an uneven coating is made even more likely. Efficient casting with viscous casting material is thus not possible utilizing any of the processes known in the art.